On 11/24/08 10:54, Larry Evans wrote:
On 11/24/08 09:46, George van Venrooij wrote: [snip] George, earlier this year, there was yet another person who had a proposed solution:
http://thread.gmane.org/gmane.comp.lib.boost.devel/171761
The OP in that thread benchmarked the solution:
http://thread.gmane.org/gmane.comp.lib.boost.devel/171761/focus=172030
I'd guess that before anything is adopted when there are several alternatives, the pros/cons and a benchmark comparing the alternatives would be desirable.
apfelmus' recent post to haskell.cafe ng provided a monadic version: sequence :: Monad m => [m a] -> m [a] {-# INLINE sequence #-} sequence ms = foldr k (return []) ms where k m m' = do { x <- m; xs <- m'; return (x:xs) } of the crossf solution posted earlier: http://news.gmane.org/gmane.comp.lang.haskell.cafe/cutoff=47985 which looks very similar to the moncow 2 sequence version: cross :: [a] -> [b] -> [(a,b)] cross ls1 ls2 = do x <- ls1 y <- ls2 return (x,y) found here: http://www.muitovar.com/monad/moncow.xhtml#list which was mentioned in my first reply. This suggests, at least to me, that monads could be useful in mpl. Anybody else think that's worth exploring?